Thermodynamic study of the aqueous mixed electrolyte system containing 1-ethy1-3-methyl imidazofium bromide ([EMIm]) and lithium bromide (LiBr) was performed on the galvanic cell of the type: [-EMIm] -ISE I [EMIm] Br (m(1)), LiBr (m(2)), H2O vertical bar Br-ISE over total ionic strengths from 0.01 to 2.25 mol kg(-1) Various series of the salt molal ratios (r = m[EMIm]Br/m(LiBr) = 0.1, 0.2, 1.0, 5.0) and [EMIm]Br single electrolyte solution Were used at T= (298.2, 303.2, 308.2 and 313.2) K and P = 0.1 MPa. The Pitzer ion interaction model was employed to determine the activity coefficients for the studied system. The Pitzer mixing interaction parameters were evaluated for the mixed electrolyte system. The obtained parameters were used to calculate the mean activity coefficients of the solute species, the osmotic coefficients and excess Gibbs free energies for the whole series of the mixed electrolyte systems. Furthermore, the temperature dependence of the excess Gibbs free energy was also applied to calculate the excess enthalpy for the electrolyte system. (C) 2016 Elsevier B.V. All rights reserved.